Isolating a transmitter in an industrial process control system is a feature used to isolate or remove industrial transmission equipment from the process for purposes of calibration, repair and routine maintenance. Such a feature maintains even greater importance where a transmitter is used to monitor high temperature and pressure service or volatile chemicals. A technician wishing to perform maintenance, may assume isolation has occurred and may begin to drain or open the transmitter. However, due to a leak or other fault with the isolation valve, the conditions may not be safe to perform needed maintenance (e.g. pressure or temperature high enough to ignite a process fluid when exposed to air), and thus causing an accident resulting in a fire or severe personal injury.
The industrial transmitters themselves may maintain processing capability locally or alternatively, or in combination, may rely upon a central microprocessing system such as a Distributed Control System (DCS). Such processing may allow the transmitter to analyze sensed parameters such as temperature and pressure to make a determination as to the condition of a monitored process fluid. Without the ability to have more than one indication from which to determine the transmitter's isolation, false indication can lead to damage and personal injury. There is a need to improve the reliability of transmitter isolation indications to reduce maintenance costs and injury. Finally, there also exists the need to provide local and remote indication as to isolation when availability of information is minimal.